The new 17-50mm F2.8 OS EX HSM by Sigma is standard zoom lens that covers a starting focal length of 17mm wide angle which provides a large f/2.8 aperture all the way through the whole zoom range, rendering it perfect for many photographic situations
particularly portraits and landscapes. The Sigma anti shake function (OS) allows using shutter speeds up to 4 stops less than could otherwise be feasible. The OS function lets Sony and Pentax shooters the option of composing a stabilized image looking through the viewfinder, a function offered by Sigma only. HSM is fast and quiet
autofocus.
Sigma 17-50mm F2.8 EX DC OS HSM Fast Zoom Lens Side View
Sigma produces their own brand FLD glass elements, that perform equal to fluorite integrated with a pair of glass mold and a single hybrid aspherical lens, combined to provide excellent adjustments for all sorts of aberrations. A Super Multi-Layer coat cuts down on flare and ghosting. Additionally the lens boasts exceptional peripheral luminance and captures crisp, high contrast photos even while at maximum aperture settings. Also the minimum focusing distance is only 11 inches all the way through the entire zoom distance and a 1:5.magnification ratio It is also possible to focus in as close as 4.7cm(1.9in.) distance from the lens tip to the scene making it particularly useful for shooting close-up photography. For those times when you need be ready for any photographic moment a fast aperture comes in handy so you can capture images in low available light or at the maximum range using a flash. It's a perfect Sigma lens with it's compact dimensions and very light in weight, making it a welcome addition to your existing camera gear
Sigma 17-50mm F2.8 EX DC OS HSM Lens Zoom View
The big F2.8 aperture rounded 7 blade diaphragm generates an attractive blurred background to out of focus zones and increases autofocus speed. The inner focusing structure eliminates rotation
of the front lens, allowing it to be particularly suitable for attaching the
included petal-style lens hood and also circular polarizing filters.
Sigma 17-50mm F2.8 EX DC OS HSM Fast Zoom Lens Mount View
Note! Vignetting will occur if the lens is used with digital cameras with image sensors larger than APS-C size or 35mm SLR cameras.
HSM means this lens will autofocus on Nikon D40/D40x,
Nikon D60, Nikon D3000,
Nikon D3100,
Nikon D5000 and the Nikon D5100 
Apr 18, 2011
Features
• For DSLRs with APS-C Size Sensors
• 4 Stops of Anti-Shake (OS) Compensation
• Aperture of f/2.8 throughout Zoom Range
• Accepts 77mm Filters
• Ultra Compact (Only 3.6", 91.8mm Long)
• Multi-Layered Lens Coating
• Excellent Correction for Aberrations
• Hyper-Sonic Motor for Quiet/Fast AF
• Close Focusing Distance of 11" (28cm)
• Weighs Only 19.9 oz (565 g)
• The DC designation for the smaller size (APS-C) of the image sensor of your digital SLR.
• Constructed with 17 elements in 13 groups, it features FLD ("F" Low
Dispersion) glass
• Sigma lenses are made in Japan.
Item Includes
• Sigma 17-50mm F2.8 EX DC OS HSM Zoom Lens
• Lens Hood
• 1-Year International Warranty plus 3 Additional Years in the USA
